Hydrogen storage materials or media (HSMs) are a class of chemicals containing hydrogen in a chemically or physically bound form. They have wide potential utility in the areas of transportation, materials manufacture and processing and laboratory research. There is particular current interest in HSMs for the first application: vehicles powered by fuel cells or internal combustion engines for use in a ‘hydrogen economy’ will require an on-board source of hydrogen fuel, and hydrogen is very difficult to store either as a gas or as a cooled liquid to provide sufficient distance between refills.
Despite optimism over the last three decades, a hydrogen economy remains a utopian vision. The US Department of Energy (DOE) Basic Science group published a landscape report in 2003 summarizing the fundamental scientific challenges that must be met before a hydrogen economy becomes viable. The report identifies the following desiderata for a viable HSM:                1. High hydrogen storage capacity (min 6.5 wt % H).        2. Low H2 generation temperature (Tdec ideally around 60-120° C.).        3. Favorable kinetics for H2 adsorption/desorption.        4. Low cost.        5. Low toxicity and low hazards.        
Alane, (AlH3)x is a polymeric network solid that contains 10.1 wt % hydrogen and undergoes dehydrogenation to simple, nontoxic Al powder. It is an excellent candidate material to meet the long term DOE hydrogen systems goals. Since the time of filing of our earlier patent application entitled SYNTHESIS, RECHARGING AND PROCESSING OF HYDROGEN STORAGE MATERIALS USING SUPERCRITICAL FLUIDS (International Pat. App. PCT/CA2005/001908), alane has become a serious contender as an HSM for vehicular hydrogen storage. However, the enthalpy of dehydrogenation of all known phases of alane indicate that direct rehydrogenation can be accomplished only at extremely high pressures, and is therefore not viable as a large-scale technology. Thus the utilization of alane as a practically viable hydrogen storage material can only be realized if alternative methods can developed for the hydrogenation of aluminum. Currently, there are no methods known to achieve this outcome, aside from the laborious, costly and wasteful route involving conversion of Al into a corresponding halide or other derivative, followed by a metathesis reaction with a saline or complex hydride, as detailed in Equations 1 and 2.Al+3LiCl+1.5H2→AlCl3+3LiH (uptake of H2)  Eq. 1AlCl3+3LiH→Al+3LiCl+1.5H2 (release of H2)  Eq. 2
These reactions can be applied in a cycle, as illustrated in Scheme 1. It is believed that the hydrogen uptake reaction given by Equation 1 converts the Al+3LiCl to AlCl3+3LiH by way of the intermediates Al+Cl2+3Li+H2 as shown on the left hand side of the cycle. It is further believed that the hydrogen release reaction given by Equation 2 converts the AlCl3+3LiH to Al+3LiCl by way of the intermediates AlH3+3LiCl as shown on the right hand side of the cycle.

Reports describing the use of alane as a chemical reagent appear in the public literature at least as early as 1947. U.S. Pat. No. 6,228,388 issued May 8, 2001 to Petrie et al. describes various methods of preparing alane using metal hydrides as a source of hydrogen.
U.S. Pat. No. 6,536,485 issued Mar. 25, 2003 to O'Brien discloses a means of room temperature packaging of hydrogen using a solvent such as ethane or hexane: large amounts of H2 gas can be dissolved in these hydrocarbons when they are in a supercritical phase. O'Brien exploits the high miscibility of hydrogen with supercritical fluids, effectively using the organic solvent as an HSM. At column 7, lines 41-42 the patent teaches that by using the systems and methods disclosed therein, “The high weight of metal hydride type storing systems is also avoided.” This statement appears to be teaching away from using metal hydrides for the storage of hydrogen.